Just like everyone over 57 or so was at Woodstock, it seems like everyone was present at the birth of the RDL.

The latest PM has an article in which Matt Foreman recollects being at the OTC in 1990:

"Then he started performing an exercise we saw him do regularly.... Somebody in the gym asked Nicu and Dragomir what the exercise was called. They said that they did not have a special name for it, and so one of the American lifters suggested that it could be called a “Romanian Deadlift” or RDL.... I’ve always considered it a privilege that I was present when the RDL was officially named."

But Jim Schmitz says that the basic scene above happened at Sports Palace in the same year, with Randall Strossen in attendance: